Experimental demonstration of sub-100 picometer level signal extraction with time-delay interferometry technique

In this work, we have built an experimental setup to simulate the clock noise transmission between two spacecrafts, and further demonstrated the extraction of picometer level signal drowned by the large laser frequency noise and clock noise with the data post-processing method. Laser frequency noise is almost eliminated by using the idea of time-delay interferometry (TDI) to construct an equal arm interferometer. Clock asynchronism and clock jitter noise are significantly suppressed by laser sideband transmitting the clock noise with an electro-optic modulator (EOM). Experimental results show a reduction in laser frequency noise by approximately 105 and clock noise by 102, recovering a weak displacement signal with an average amplitude about 60 picometer and period 1 s. This work has achieved the principle verification of the noise reduction function of TDI technique to some extent, serving the data processing research of space-borne gravitational wave detection.